Conventionally, hydrofluorocarbon (HFC) based refrigerants have been used as the refrigerants for heat pump devices and organic Rankine cycle devices. HFC-based refrigerants have an ozone layer depletion coefficient of zero, and have high thermal stability. However, HFC-based refrigerants have an extremely high global warming potential (GWP). As a result, the use of HFC-based refrigerants is undesirable from the viewpoint of global environmental protection.
Examples of known refrigerants having a low GWP include hydrofluoroolefin (HFO) and hydrochlorofluoroolefin (HCFO) based refrigerants. Patent Literature 1 (PTL 1) discloses a refrigeration cycle device which uses a refrigerant containing mainly an HFO. In PTL 1, the compound 2,3,3,3-tetrafluoro-1-propene (HFO1234yf) is used as the HFO-based refrigerant.
Isomers exist for some HFO and HCFO compounds. For example, a regioisomer 1,3,3,3-tetrafluoro-1-propene (HFO1234ze) exists for HFO1234yf. Further, for HFO1234ze, the cis-trans isomers of HFO1234ze(Z) and HFO1234ze(E) exist.